Carbon-hydrocarbon gas composite fuels

ABSTRACT

A composition includes a porous carbon substrate; a hydrocarbon gas; a sealant configured to retain the hydrocarbon gas with at least a portion of the porous carbon substrate. Such a composition is known as a carbon-hydrocarbon gas composite. Another composition includes the carbon-hydrocarbon gas composite and fuel. Such fuels include diesel.

CROSS REFERENCE TO RELATED APPLICATIONS

The application claims the benefit of U.S. Provisional Application No. 61/739,447, filed on Dec. 19, 2012, and which is incorporated herein by reference for any and all purposes.

FIELD

This invention generally relates to fuels, and more particularly to fuels containing a carbon-hydrocarbon gas composite.

SUMMARY

In one aspect, a composition is provided including a porous carbon substrate; a hydrocarbon gas; and a sealant a sealant configured to retain the hydrocarbon gas with at least a portion of the porous carbon substrate. In some embodiments, the hydrocarbon gas includes a C₁-C₅ hydrocarbon gas. In some embodiments, the sealant includes heavy tar, coal pitch, starch, sugar, or a mixture of any two or more such materials.

In any of the above embodiments, a portion of the hydrocarbon gas may be adsorbed on a surface of the porous carbon substrate. In any of the above embodiments, the porous carbon substrate may be a microporous carbon substrate. For example, the porous carbon substrate may include graphite, graphene, mesoporous carbon, mesoporous microcarbon microbeads, amorphous carbon, coal, pulverized coal, biomass, plastic resins, polymers, or waste materials.

In any of the above embodiments, the composition may include up to 80 wt % of the hydrocarbon gas. For example, the composition may include up to 50 wt % of the hydrocarbon gas.

In another aspect, a process of preparing a carbon-hydrocarbon gas composite includes exposing a porous carbon substrate to a pressurized hydrocarbon gas to form a carbon-hydrocarbon gas material; and coating the carbon-hydrocarbon gas material with a sealant.

In another aspect, a composition includes a fuel; and a carbon-hydrocarbon gas composite including a porous carbon substrate; a hydrocarbon gas; a sealant configured to retain the hydrocarbon gas with at least a portion of the porous carbon substrate; wherein the composition is a fuel composite.

In another aspect, a process of preparing a composition includes mixing a fuel with a carbon-hydrocarbon gas composite; wherein the carbon-hydrocarbon gas composite includes a porous carbon substrate; a hydrocarbon gas; a sealant configured to retain the hydrocarbon gas with at least a portion of the porous carbon substrate; wherein the composition is a fuel composite.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the production of a composite fuel, according to one embodiment.

FIG. 2 is a schematic, progression illustration of a hydrocarbon gas in a porous carbon substrate, according to one embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here.

The technology is described herein using several definitions, as set forth throughout the specification.

As used herein, unless otherwise stated, the singular forms “a,” “an,” and “the” include plural reference. Thus, for example, a reference to “a gas” includes one or more gases, and a reference to “a molecule” is a reference to one or more molecules.

As used herein, “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, “about” will mean up to plus or minus 10% of the particular term.

In one aspect, a carbon-hydrocarbon gas composite (CHGC) is provided. The composites include a porous carbon substrate, a hydrocarbon gas adsorbed onto a surface of the carbon substrate, and a sealant. It is known that upon exposure of a porous carbon substrate to a hydrocarbon gas, the gas will adsorb onto the external and internal surfaces of the substrate. However, upon release of the pressure, the majority of the gas will desorb leaving only a residual amount of the gas. In the present composites, after adsorption of the gas onto the substrate, but before de-pressurization, the substrate-gas material is coated with a sealant, thereby preventing, or at least minimizing, desorption of the gas from the substrate upon de-pressurization. Thus, in one embodiment, a composition includes a porous carbon substrate, a hydrocarbon gas, and a sealant. In one embodiment, the sealant is configured to retain the hydrocarbon gas with at least a portion of the porous carbon substrate. For example, the sealant may plug a pore of the carbon substrate, thereby entrapping the gas within the pore, or the sealant may be applied over an outer surface of the carbon substrate, where a molecule of hydrocarbon gas is adsorbed, thereby trapping the adsorbed gas molecule to the outer surface of the substrate. In another aspect, the CHGC is combined with a fuel to provide a fuel composite.

As used herein, and unless expressly stated otherwise, the surface of the substrate includes not only the outer surface, but also any surface within the porous structure.

FIG. 1 describes the general overall process for preparing the CHGC and a fuel composite containing the CHGC. As illustrated, a porous carbon substrate is introduced to a pressurizable chamber. The chamber also provides for introduction of a pressurized gas that includes, but is not necessarily limited to, a hydrocarbon gas, and optionally, pore-filling enhancers. Under pressure, the hydrocarbon gas adsorbs onto the surface of the carbon substrate and into the pores of the carbon substrate, along with any of the enhancers, if present. Once the hydrocarbon gas has been adsorbed, the substrate is coated with a sealant to form the CHGC. At this juncture, the CHGC may either be introduced to the fuel under pressure, or the CHGC is depressurized and then added to the fuel.

FIG. 2 is a schematic illustration of a CHGC 100 as it progresses from unfilled, porous carbon substrate to a CHGC suspended in a fuel. An individual pore 110 of a carbon substrate is filled with hydrocarbon gas 140 under pressure. Optionally, pore-filling enhancers may also be deposited in the carbon pore 110 along with the hydrocarbon gas 140. The pore 110 is then sealed under pressure with a sealant 150, thereby sequestering the hydrocarbon gas 140 and any optional, pore-filling enhancers within the pore 110. In one embodiment, and as illustrated in the figure, the CHGC 100 is then suspended in a fuel 160. The fuel 160 contains the CHGC 100 and can be used at ambient temperature and/or pressure without loss of the hydrocarbon gas.

Suitable porous carbon substrates include those that have a high surface area, and, preferably a low ash content. For example, the surface area (N₂-BET surface area) of the carbon may be greater than 150 m²/g, greater than 250 m²/g, greater than 500 m²/g, or greater than 1000 m²/g. In some embodiments, the surface area is from about 250 m²/g to about 500 m²/g, or from about 500 m²/g to about 2000 m²/g. With regard to the ash content, in some embodiments, it is less than 10 wt %, less than 5 wt %, less than 2 wt %, or less than 1 wt %. In other embodiments, the ash content of the porous carbon substrate is from 0 to about 5 wt %, or from 0 to about 2 wt %.

Suitable porous carbon substrates may be derived from biomass, coal or petroleum sources. Using carbon that originates from biomass is a “green” use of material that may otherwise be waste. Suitable porous carbon substrates include, but are not limited to, those that are predominantly microporous. As used herein, microporous refers to an activated carbon where the majority of its surface area and pore volume are from micropores (i.e., pores with diameters less than 2 nm). In some embodiments, the particles size of the carbon is macroscopic, on the mm scale. For example, in one embodiment, the particle size of the carbon is from 1-3 mm during the adsorption and coating process, however, the composite may then be pulverized to a size less than 20 μm.

The pore sizes of the individual particles of the substrate have average sizes ranging from about 0.4 nm to about 100 nm, according to some embodiments. In other embodiments, the size of the pores is less than 2 nm. In yet other embodiments, the pores range in size from about 0.4 nm to about 2 nm. In some embodiments, the micropores have an average diameter of from about 0.6 nm to about 2 nm. The carbon substrate may also be mesoporous. As used herein, mesoporous materials are those having pores with an average diameter of from about 2 nm to about 50 nm. In some embodiments, the mesoporous substrate has pores with an average diameter of from about 3 nm to about 30 nm. Such sizes are well suited to adsorption of methane within the pores, with methane having a molecular diameter of about 0.382 nm. Such size ranges of methane allow for more than a single layer of the adsorbing gas, e.g. methane, to adsorb to the pore surface. For example, in some embodiments, two layers of methane adsorb to the pore surface. For materials having a pore size outside of the range for a microporous or mesoporous structure, the pore size is designated.

Without being bound by theory, there are two reasons why the porous structure of the adsorbents determines the gas adsorption capacity. First, the structure of the CH₄ molecule is highly symmetrical, and can be considered as a sphere. Second, CH₄ molecules have a negligible quadrupole moment. For those molecules with weak quadrupole interaction, a change in the oxygenated functionality of the adsorbent surface would not greatly affect the adsorption capacity. Therefore, the effect of hetero-atoms or functionality on CH₄ storage onto microporous carbon is not critical. Thus, the porous structure is primarily responsible for trapping the gas within the pore, and not gas-carbon interactions binding the gas into the pore, other than weak van der Waal's interactions.

Generally the gas adsorption capacity of a porous carbon substrate (g gas/g carbon) increases with increasing micropore volume of carbon. Generally, the absorption capacity decreases with increasing temperature and increases with increasing pressure. For example at 25° C., the methane adsorption capacity of Norit R1 Extra (a peat-based activated carbon with SA_(BET)=1450 m²/g, pore volume=0.47 cm³/g) is about 1% at 0.1 MPa methane pressure, 7% at 1.5 MPa methane pressure, and 9% at 3 MPa methane pressure. A gravimetric or a volumetric adsorption system may be used to measure methane adsorption isotherm of carbon by measuring the mass or pressure of a system before and after gas contact with the substrate. An adsorption isotherm curve is prepared by plotting the adsorption capacity against the equilibrium methane pressure at a constant temperature. The reverse of the procedure will produce a desorption isotherm. If the adsorption and desorption isotherms are identical, the adsorption is reversible. If the desorption isotherm represent a hysteresis, then less gas is released from the substrate at a specific equilibrium pressure. The shape of pore, among other factors, is believed to impact such hysteresis.

According to one embodiment, a suitable porous carbon substrate will exhibit a hysteresis with respect to the gas that is to be adsorbed. This is because less of the gas will be potentially released when the substrate saturated with the gas at high pressure is depressurized to atmospheric pressure. Therefore, pore size distribution of the substrate will have both a large micropore volume and some mesoporosity to promote gas retention.

According to various embodiments, the porous carbon substrate is graphite, graphene, mesoporous carbon, mesoporous microcarbon microbeads, amorphous carbon, different types of activated carbons derived from coal, pulverized coal, biomass, plastic resins, polymers, waste materials, or other forms of porous carbon. The porous carbon substrate may be a carbon material as prepared, or the carbon material may be pulverized. For example, where coal is used as a source for the carbon substrate, it may be pulverized coal. It may also be treated by heating to an elevated temperature and/or exposing the pulverized coal to a vacuum to remove low molecular weight gases and materials that would inhibit or reduce hydrocarbon gas adsorption.

Suitable hydrocarbon gas sources include, but are not limited to natural gas sources and purified gas sources. The hydrocarbon gas may include any of the C₁ to C₅ hydrocarbons, which are both unsubstituted and substituted. For example, the hydrocarbon gas may be an alkane such as, but not limited to, methane, ethane, propane, butane, isobutane, pentane, isopentane, or neopentane. The hydrocarbon gas may also include, but is not limited to C₁ to C₅ oxygenated hydrocarbon gases such as methylether or methylethylether. The hydrocarbon gas may be, but is not limited to any such mixture of one or more alkanes, one or more oxygenated hydrocarbons, or one or more alkanes with one or more oxygenated hydrocarbons. As used herein, a C₁-C₅ gas is one in which there are from one to five carbon atoms. There may be other atoms in addition to carbon and hydrogen as well, for example, halogen atoms, nitrogen, sulfur, phosphorus, or oxygen are just a few examples. In some embodiments, the hydrocarbon gas includes methane. The adsorption may also be performed with a wet hydrocarbon gas to form a gas-carbon hydrate material.

As noted above, the hydrocarbon gas is pressurized when exposed to the porous carbon substrate. The pressure of the hydrocarbon gas may be greater than 1 atm. For example, the pressure may be greater than 5 atm, greater than 10 atm, greater than 20 atm, greater than 50 atm, or greater than 100 atm. In some embodiments, the pressure may be from about 5 atm to about 50 atm. The pressure will depend at least in part on the type of carbon substrate, with some carbon substrates requiring higher pressures for hydrocarbon gas adsorption than others. In other embodiments, the pressure is about from about 5 atm to about 200 atm.

The exposure (e.g. the adsorption) is conducted at any temperature at which the hydrocarbon gas will adsorb to a surface of the porous carbon substrate. For example, the temperature may be at ambient temperature. In other embodiments, the temperature may be below ambient temperature, or above ambient temperature. For example, the temperature may be from −196° C. to about 200° C. In some embodiments, the temperature may be from about −40° C. to about 100° C. In one embodiment the temperature is from about 23° C. to about 35° C. In another embodiment the temperature is from about −20° C. to about 20° C.

In some embodiments, to enhance the adsorption capacity of the gas onto the larger pores of a porous carbon substrate, where the gas is not efficiently trapped, a pore-filling enhancer may be used. Such pore filling enhancers include hydrocarbons, or mixtures, to solubilize the gas and incorporate more gas into the substrate within the larger pores. In such a case, the substrate is first exposed to the pore-filling enhancer and the exposed to the pressurized gas. For example, in one embodiment, the pore-filling enhancer is diesel fuel and the gas is methane. In such example, the pores of the carbon substrate are first filled with the diesel fuel, then substrate is exposed to high pressure methane. With this approach, the methane is adsorbed into the small micropores (e.g., pore diameter<2 nm) that are not accessible to larger hydrocarbon molecules. Furthermore, the methane will dissolve in the hydrocarbon that has occupied the meso and macropores and trap the methane within these larger voids.

Other pore filling enchancers include the use of water to form a methane hydrate. Methane adsorption onto a wet activated carbon is higher compared to a dry activated carbon at pressures above 4 MPa. In addition to water, other molecules that can form cages for entrapping methane can be considered for enhancing methane adsorption at high pressures.

Illustrative pore-filling enhancers include, but are not limited to, water, alcohols, diesel fuel, hydrocarbons, and other organic/inorganic enhancers such as halogenated compounds that increase the retention and solubility of methane in the liquid phase or enhance methane adsorption onto the carbon. Illustrative alcohols include, but are not limited to, methanol, ethanol, propanol, and iso-propanol. Illustrative halogenated compounds include, but are not limited to, dichloromethane, chloroform, carbon tetrachloride, trichloroethane, trichloroethylene, freons, chlorofluorocarbons, hydrofluorocarbons, hydrochlorofluorocarbons, and the like.

The sealant may be any material that is suitable for retaining the hydrocarbon gas within the pores of the porous carbon substrate. Where the carbon-hydrocarbon gas composite (CHGC) is to be used in a fuel, the sealant is negligibly soluble in the fuel. By negligibly soluble, it is meant that the sealant is insoluble in the fuel, or is so poorly soluble that the entrapped gas is not released from the porous carbon substrate when the fuel contacts the hydrocarbon gas-carbon composite. For example, illustrative sealants include, but are not limited to, heavy tar, coal pitch, starch, sugar, corn syrup, glucose, fructose, oligosaccharides, synthetic or natural polymers, or a mixture of any two or more such materials. Where the sealant is a sugar, the sugar may include, but is not limited to, glucose, fructose, sucrose, lactose, corn syrup, or a mixture of any two or more thereof.

In another aspect, a composite fuel is provided including a fuel and any of the CHGCs described above. Such composite fuels may burn cleaner than the fuel alone and provide engine protection. Such fuels may also increase the horsepower of an engine which burns the composite fuel, when compared to burning the fuel alone. Such composite fuels may also increase the mileage of an engine when compared to the engine burning the fuel alone.

Suitable fuels may include gasoline, diesel, kerosene, jet fuel, fuel oil, ethanol supplemented fuels such as E15 and E85, biofuels, vegetable oils, and the like. In one embodiment, the fuel is gasoline. In another embodiment, the fuel is diesel.

The fuel composite has a CHGC content such that the fuel composite has a comparable, or higher heating value than the fuel alone, and which generates fewer air pollutants per Btu (British Thermal Unit) than a engine burning the fuel alone. For example, the fuel composite may contain up to about 70 wt % CHGC. In various embodiments, the fuel composite contains up to about 60 wt % CHGC, up to about 50 wt % CHGC, up to about 40 wt % CHGC, or up to about 30 wt %, or up to about 20 wt %, or up to about 10 wt %. In other embodiments, the fuel composite contains from about 1 wt % to about 70 wt % CHGC. In other embodiments, the fuel composite contains from about 10 wt % to about 40 wt % CHGC. In some embodiments, the fuel composite contains about 10 wt % CHGC. In other embodiments, the fuel composite contains about 20 wt % CHGC. In some embodiments, the fuel composite contains about 30 wt % CHGC. In other embodiments, the fuel composite contains about 40 wt % CHGC. In some embodiments, the fuel composite contains about 50 wt % CHGC. In other embodiments, the fuel composite contains about 60 wt % CHGC.

The fuel composite may be prepared at any suitable temperature or pressure. However, because the hydrocarbon gas is trapped within the CHGC, the CHGC may either be added to the fuel at ambient temperature or pressure (i.e. about 25° C. and about 1 atm), or the CHGC and fuel may be mixed at elevated pressures, and then de-pressurized to ambient conditions after mixing.

In another aspect, a process is provided for preparing the CHGC and a fuel composite containing the CHGC, as generally described by FIG. 1. Thus, in one embodiment, the process includes exposing a porous carbon substrate to a pressurized hydrocarbon gas to form a carbon-hydrocarbon gas material, and coating the carbon-hydrocarbon gas material with a sealant. According to some embodiments, the exposing is conducted at a pressure of greater than 1 atm. In other embodiments, the exposing is conducted at a pressure of greater than 5 atm. In yet other embodiments, the exposing is conducted at a pressure of from 10 atm to 500 atm. Where the carbon substrate may have contaminants or other materials within the porous structure, those other materials may be removed by heating, applying a vacuum, or both.

In some embodiments of the process, the coating includes contacting the sealant in a liquid with the carbon-hydrocarbon gas material, and then solidifying the sealant (by cooling or solvent evaporation) to form a CHGC. The liquid state of any of the sealants or coatings may be a molten state of the coating or sealant. Upon solidifying, the sealant effectively sequesters the hydrocarbon gas within or on the carbon substrate such that at ambient temperatures and pressures, the hydrocarbon gas does not release from the CHGC. The temperature at which the sealant and carbon-hydrocarbon gas material are introduced may be elevated to melt the sealant such that it is in a liquid state. For example, the temperature at which the sealant and carbon-hydrocarbon gas material are introduced may be from about 20° C. to about 350° C. In some embodiments, the temperature at which the sealant and carbon-hydrocarbon gas material are introduced is from about 100° C. to about 300° C. In other embodiments, the temperature at which the sealant and carbon-hydrocarbon gas material are introduced is from about 200° C. to about 300° C.

In other embodiments of the process, the coating includes contacting the sealant as a solution in a solvent with the carbon-hydrocarbon gas material. The solvent may either be absorbed into the carbon-hydrocarbon gas material and coating, or it may be evaporated from the composite. Upon absorption or evaporation of the solvent to solidify the sealant as either a crystalline or amorphous solid, a CHGC is formed. Upon solidifying, the sealant effectively sequesters the hydrocarbon gas within or on the carbon substrate such that at ambient temperatures and pressures, the hydrocarbon gas does not release from the CHGC. The solution of the sealant may be sprayed onto the surface of carbon-hydrocarbon gas material, and potentially, into a portion of the internal pores. During spraying, the carbon-hydrocarbon gas material will be agitated to provide for a somewhat uniform coating of each individual carbon particle, and to avoid, or at least minimize, agglomeration of the material. Suitable solvents include, but are not limited to, water, an alcohol, an alkane, an alkene, aromatic hydrocarbon, or a halogenated hydrocarbon. For example, the solvent may include, but is not limited to, water, methanol, ethanol isopropanol, pentane, hexane, octane, benzene, toluene, dichloromethane, chloroform, carbon tetrachloride, trichloroethane, trichloroethylene, freons, chlorofluorocarbons, hydrofluorocarbons, hydrochlorofluorocarbons, and the like.

As noted above, illustrative sealants include, but are not limited to, heavy tar, coal pitch, starch, sugar, or a mixture of any two or more such materials. Where the sealant is a sugar, the sugar may include, but is not limited to, glucose, fructose, sucrose, lactose, corn syrup, oligosaccharides, synthetic or natural polymers, or a mixture of any two or more such materials. As an illustration of the process where the sealant is a sugar, the sugar is heated to a temperature sufficient to cause the sugar to be in a liquid state, whereupon the liquid sugar and the carbon-hydrocarbon gas material are introduced. Upon cooling to ambient temperature, the sugar solidifies and coats the material to form the CHGC composite.

In another aspect, a process is provided for a fuel composite, as generally described, in part, by FIG. 1. Thus, in one embodiment, the process includes mixing a fuel with a carbon-hydrocarbon gas composite, where the carbon-hydrocarbon gas composite is as described above. As illustrated in FIG. 1, the process of mixing may be performed either at elevated pressure, or at ambient pressure. Thus, in one embodiment, while under pressure, the fuel may be added to the CHGC, or the CHGC added to the fuel, and then a controlled release of the pressure is performed until ambient pressure conditions are reached. In another embodiment, the pressure on the CHGC is released in a controlled manner and then the fuel is mixed with the CHGC at ambient pressure. As used with respect to the mixing, ambient pressure is about 1 atm, or as that pressure may fluctuate due to changes in elevation.

The mixing of the fuel and the CHGC, whether under pressure or at ambient pressure, may be conducted at any convenient temperature. In one embodiment, the mixing is conducted at ambient temperature. As used with respect to the mixing, ambient temperature is the environmental temperature in which the mixing chamber is located. In some embodiments, the mixing may be conducted at a temperature of from about 0° C. to about 100° C. In some embodiments, the mixing is conducted at a temperature from about 20° C. to about 35° C.

To maintain the integrity of the sealant, the coating should be negligibly soluble in the fuel.

To aid in dispersion of the CHGC in the fuel, a dispersant may be used. Suitable dispersants may include, but are not limited to, lignosulfates, or synthetic/natural polymeric dispersants. In some embodiments, a lignosulfate dispersant is used.

The present technology, thus generally described, will be understood more readily by reference to the following examples, which are provided by way of illustration and are not intended to be limiting of the present technology.

Examples

Example 1. Adsorption and trapping of methane onto and into porous carbon using a solvent soluble sealant. A porous carbon material having a low ash content (<5 wt %) is to be used. The initial size of the carbon particles may be on the order of several mm, however the material may be pulverized to a particle size of less than about 10 to 20 μm. A pre-weighed amount (1 to 100 g) of granular carbon (0.001 to 5 mm) will be placed inside a pressurizable chamber, at ambient temperature. One such laboratory-scale pressurizable chamber is known as a Parr reactor, available from the Parr Instrument Company, Moline, Ill. The reactor is to be pressurized to a desired pressure with methane to achieve an acceptable adsorption capacity based on a pre-determined adsorption isotherm. After the pressure in the reactor has stabilized (i.e. equilibrium is reached), a sealant solution is sprayed into the pressurized reactor using a pump while the carbon is being stirred. One illustrative pump that may be used is a pump as used for high performance liquid chromatograph (HPLC). It may be necessary to heat the solution to increase the solubility of the active compounds in the solution. The solvent is then removed under methane pressure with heat or alternatively an anti-solvent for the sealant is added to precipitate the sealant over the carbon pores. The pressure in the Parr reactor will then be released (to atmospheric pressure) and the composite samples collected.

Example 2. Adsorption and trapping of methane onto and into porous carbon using a polymerizable sealant. A porous carbon material having a low ash content (<5 wt %) is to be used. The initial size of the carbon particles may be on the order of several mm, however the material may be pulverized to a particle size of less than about 10 to 20 μm. A pre-weighed amount (1 to 100 g) of granular carbon (0.001 to 5 mm) will be placed inside a Parr reactor at ambient temperature. The reactor is to be pressurized to a desired pressure with methane to achieve an acceptable adsorption capacity based on a pre-determined adsorption isotherm. After the pressure in the reactor has stabilized (i.e. equilibrium is reached), a polymerizable sealant solution, such as sucrose, is sprayed into the Parr reactor using a HPLC pump while the carbon is being stirred. The solution is heated while under pressure to polymerize the sealant and coat or precipitate the polymerized sealant over the carbon pores. The pressure in the Parr reactor will then be released (to atmospheric pressure) and the composite samples collected.

Example 3. Adsorption and trapping of methane onto and into pulverized coal using a sealant. Pulverized coal of average particle size of less than about 10 to 20 μm is to be placed inside a Parr reactor at ambient temperature. The reactor is to be pressurized to a desired pressure with methane to achieve an acceptable adsorption capacity based on a pre-determined adsorption isotherm. The sealing and depressurizing may be conducted as above in Examples 1 and 2.

Example 4. Adsorption and trapping of methane onto and into pulverized coal using a sealant. Pulverized coal of average particle size of less than about 10 to 20 μm is to be placed inside a Parr reactor at ambient temperature, and the reactor is evacuated, is heated to a temperature from about 200° C. to about 350° C., or both evacuated and heated. This process degasses the coal, removing low molecular weight gases that are trapped inside the coal particles. The reactor is to be pressurized to a desired pressure with methane to achieve an acceptable adsorption capacity based on a pre-determined adsorption isotherm. The sealing and depressurizing may be conducted as above in Examples 1 and 2.

Example 5. Measuring Methane Content of the Coated Methane-Loaded Carbon. The methane content of composite of Example 1 may be measured by two methods. In the first method, the heat value of the methane-loaded carbon and a nitrogen-loaded carbon (same carbon treated exactly like the methane-loaded carbon but exposed to high pressure nitrogen instead of methane) are measured and the amount of loaded methane is calculated from the heat value difference. In the second method, methane content of samples can be directly measured by monitoring the carbon-hydrogen bond stretches or bends using FTIR (Fourier Transform Infrared). For example, the absorbances at and around 2900 to 3200 cm⁻¹ and 1250 to 1400 cm⁻¹ may be monitored.

Example 6. Grinding Methane-Loaded Carbon Particles. The composite from Examples 1, 2 and 3 will be pulverized in a low impact (low energy) mill to reduce particle size to about 0.1-10 μm. The micronized carbon samples will also be characterized for their methane contents. It is expected that some of the adsorbed methane will be released during the milling process due to breaching of the sealant. Optimization of milling time and the desired particle size of carbon product will be conducted to minimize methane released during the milling process.

Example 7. Diesel-CGHC Fuel. The fuel is prepared by mixing a fuel as described in Examples 1, 2, 3 or 4 with a diesel fuel. An optional additive may also be included to prevent, or minimize, settling of the solid particles during long storage periods. The heating values of the solid portion of various fuels (not including the diesel) are listed in the following table:

Fuel Heating Value (Btu/lb) Coal 12,000 Coal volatile matter 15,000 Biomass 6,000 Activated coal charcoal 10,000 Methane 24,000 Diesel 19,500 80 wt % diesel and 18,000 20 wt % coal 80 wt % activated coal charcoal and 12,800 20 wt % adsorbed methane 80 wt % diesel and 20 wt % methane- 17,000 loaded activated carbon (20% loading) 80 wt % diesel and 20 wt % methane- 20,000 saturated coal This example illustrates that a low ash, high volatile matter coal could potentially be an alternative and attractive fuel to be blended with diesel to prepare a composite fuel. The heating value of such a fuel is comparable to a that of an adsorbed natural gas carbon containing 20 wt % methane.

The embodiments, illustratively described herein, may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms ‘comprising,’ ‘including,’ ‘containing,’ etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Additionally, the phrase ‘consisting essentially of’ will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase ‘consisting of’ excludes any element not specified.

The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent compositions, apparatuses, and methods within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as ‘up to,’ ‘at least,’ ‘greater than,’ ‘less than,’ and the like, include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member.

While certain embodiments have been illustrated and described, it should be understood that changes and modifications can be made therein in accordance with ordinary skill in the art without departing from the technology in its broader aspects as defined in the following claims. 

What is claimed is:
 1. A composition comprising: a porous carbon substrate; a hydrocarbon gas; and a sealant configured to retain the hydrocarbon gas in at least a portion of the porous carbon substrate when the composition is exposed to atmospheric pressure.
 2. The composition of claim 1, wherein a portion of the hydrocarbon gas is adsorbed on a surface of the porous carbon substrate.
 3. The composition of claim 1, wherein the porous carbon substrate is a microporous carbon substrate.
 4. The composition of claim 1, wherein the porous carbon substrate comprises graphite, graphene, mesoporous carbon, mesoporous microcarbon microbeads, amorphous carbon, coal, pulverized coal, biomass, plastic resins, polymers, or waste materials.
 5. The composition of claim 1, wherein the hydrocarbon gas comprises methane, ethane, propane, butane, isobutane, pentane, isopentane, neopentane, methylether, methylethylether, or a mixture of any two or more thereof.
 6. The composition of claim 1, wherein the hydrocarbon gas comprises methane.
 7. The composition of claim 1, wherein the sealant comprises heavy tar, coal pitch, a starch, a sugar, or a mixture of any two or more such materials.
 8. The composition of claim 1 comprising up to 80 wt % of the hydrocarbon gas.
 9. A process of preparing a carbon-hydrocarbon gas composite comprising: exposing a porous carbon substrate to a pressurized hydrocarbon gas to form a carbon-hydrocarbon gas material; coating the carbon-hydrocarbon gas material with a sealant.
 10. The process of claim 9, wherein the exposing is conducted at a pressure of from 10 atm to 500 atm.
 11. The process of claim 9, wherein the coating comprises contacting the sealant in a liquid state with the carbon-hydrocarbon gas material; and solidifying the sealant.
 12. The process of claim 11, wherein the temperature of the contacting step is sufficient to maintain the sealant in the liquid state.
 13. The process of claim 11, wherein solidifying comprises cooling the sealant and carbon-hydrocarbon gas material.
 14. The process of claim 9, wherein the sealant is dissolved in a solvent as a solution, and the coating comprises spraying the solution on the carbon-hydrocarbon gas material and removing the solvent.
 15. A composition comprising: a fuel; and a carbon-hydrocarbon gas composite comprising: a porous carbon substrate; a hydrocarbon gas; a sealant configured to retain the hydrocarbon gas with at least a portion of the porous carbon substrate; wherein the composition is a fuel composite.
 16. The composition of claim 15, wherein the fuel comprises gasoline, diesel, kerosene, jet fuel, fuel oil, ethanol supplemented fuels such as E15 and E85, or biofuels and vegetable oils.
 17. The composition of claim 15, wherein the fuel comprises diesel.
 18. A process of preparing a composition comprising: mixing a fuel with a carbon-hydrocarbon gas composite; wherein the carbon-hydrocarbon gas composite comprises: a porous carbon substrate; a hydrocarbon gas; a sealant configured to retain the hydrocarbon gas with at least a portion of the porous carbon substrate; wherein the composition is a fuel composite.
 19. The process of claim 18, wherein the mixing further comprises mixing the fuel and the carbon-hydrocarbon gas composite with a dispersant or surfactant. 